Asphalt roof sheeting is typically used as a single ply roofing membrane for industrial and commercial flat roofs. These membranes are usually processed into sheeting rolls and applied to roofs in long strips. Ordinarily, these sheets are joined to each other and to the substrate by heating, usually with a torch, so as to create a continuous roofing surface.
Asphalt roof sheeting is typically used as a single ply roofing membrane for industrial and commercial flat roofs. These membranes are usually processed into sheeting rolls and applied to roofs in long strips. Installation of these membranes requires adjoining the strips together to form a continuous roofing surface. These membranes are typically adjoined by using some form of adhesive or, more desirably, by heating.
Elasticity and flexibility facilitate processing, installation and most importantly overall use of the asphalt membrane. It is well known in the art to add synthetic or natural polymeric material to the asphalt-based membrane, thereby achieving elasticity and flexibility. Typically, vinyl containing polymers are added to accomplish such results.
Although the addition of vinyl containing polymers results in the desired flexibility and elasticity, their addition has at the same time limited the methods which can be used to adjoin the seams. Ideally, the seams are torched or heated which slightly melts the membranes allowing them to flow together. The vinyl containing polymers, however, will crosslink in the presence of high heat, thus inhibiting the ability of the membranes to flow together. Further, crosslinking causes the viscosity of the membrane to increase, decreasing the melt flow of the membrane which adds further obstacle to adjoining the membranes. As a result, other methods of adhesion are employed to adjoin the seams of vinyl containing membranes, a typical example being the use of a bonding adhesive.
It is believed that heat and ultra violet (UV) radiation promote crosslinking of the vinyl containing polymers. Thus, in addition to presenting problems during installation, crosslinking of the vinyl polymers creates problems throughout the life of the membrane since roofing surfaces are exposed to heat and UV light from the sun's rays. This long term crosslinking coupled with the crosslinking experienced during installation serves to shorten the life of the roofing membrane.
Finally, the addition of vinyl polymers, which are typically uncured, presents further installation problems in that the membranes are often unworkable. Thus, while a flexible and elastomeric roofing compound is desired, those membranes containing uncured polymers are often too soft and lack a workable stiffness and hardness.